1 // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. See the AUTHORS file for names of contributors.
4
5 #include "leveldb/cache.h"
6
7 #include <vector>
8
9 #include "gtest/gtest.h"
10 #include "util/coding.h"
11
12 namespace leveldb {
13
14 // Conversions between numeric keys/values and the types expected by Cache.
EncodeKey(int k)15 static std::string EncodeKey(int k) {
16 std::string result;
17 PutFixed32(&result, k);
18 return result;
19 }
DecodeKey(const Slice & k)20 static int DecodeKey(const Slice& k) {
21 assert(k.size() == 4);
22 return DecodeFixed32(k.data());
23 }
EncodeValue(uintptr_t v)24 static void* EncodeValue(uintptr_t v) { return reinterpret_cast<void*>(v); }
DecodeValue(void * v)25 static int DecodeValue(void* v) { return reinterpret_cast<uintptr_t>(v); }
26
27 class CacheTest : public testing::Test {
28 public:
Deleter(const Slice & key,void * v)29 static void Deleter(const Slice& key, void* v) {
30 current_->deleted_keys_.push_back(DecodeKey(key));
31 current_->deleted_values_.push_back(DecodeValue(v));
32 }
33
34 static constexpr int kCacheSize = 1000;
35 std::vector<int> deleted_keys_;
36 std::vector<int> deleted_values_;
37 Cache* cache_;
38
CacheTest()39 CacheTest() : cache_(NewLRUCache(kCacheSize)) { current_ = this; }
40
~CacheTest()41 ~CacheTest() { delete cache_; }
42
Lookup(int key)43 int Lookup(int key) {
44 Cache::Handle* handle = cache_->Lookup(EncodeKey(key));
45 const int r = (handle == nullptr) ? -1 : DecodeValue(cache_->Value(handle));
46 if (handle != nullptr) {
47 cache_->Release(handle);
48 }
49 return r;
50 }
51
Insert(int key,int value,int charge=1)52 void Insert(int key, int value, int charge = 1) {
53 cache_->Release(cache_->Insert(EncodeKey(key), EncodeValue(value), charge,
54 &CacheTest::Deleter));
55 }
56
InsertAndReturnHandle(int key,int value,int charge=1)57 Cache::Handle* InsertAndReturnHandle(int key, int value, int charge = 1) {
58 return cache_->Insert(EncodeKey(key), EncodeValue(value), charge,
59 &CacheTest::Deleter);
60 }
61
Erase(int key)62 void Erase(int key) { cache_->Erase(EncodeKey(key)); }
63 static CacheTest* current_;
64 };
65 CacheTest* CacheTest::current_;
66
TEST_F(CacheTest,HitAndMiss)67 TEST_F(CacheTest, HitAndMiss) {
68 ASSERT_EQ(-1, Lookup(100));
69
70 Insert(100, 101);
71 ASSERT_EQ(101, Lookup(100));
72 ASSERT_EQ(-1, Lookup(200));
73 ASSERT_EQ(-1, Lookup(300));
74
75 Insert(200, 201);
76 ASSERT_EQ(101, Lookup(100));
77 ASSERT_EQ(201, Lookup(200));
78 ASSERT_EQ(-1, Lookup(300));
79
80 Insert(100, 102);
81 ASSERT_EQ(102, Lookup(100));
82 ASSERT_EQ(201, Lookup(200));
83 ASSERT_EQ(-1, Lookup(300));
84
85 ASSERT_EQ(1, deleted_keys_.size());
86 ASSERT_EQ(100, deleted_keys_[0]);
87 ASSERT_EQ(101, deleted_values_[0]);
88 }
89
TEST_F(CacheTest,Erase)90 TEST_F(CacheTest, Erase) {
91 Erase(200);
92 ASSERT_EQ(0, deleted_keys_.size());
93
94 Insert(100, 101);
95 Insert(200, 201);
96 Erase(100);
97 ASSERT_EQ(-1, Lookup(100));
98 ASSERT_EQ(201, Lookup(200));
99 ASSERT_EQ(1, deleted_keys_.size());
100 ASSERT_EQ(100, deleted_keys_[0]);
101 ASSERT_EQ(101, deleted_values_[0]);
102
103 Erase(100);
104 ASSERT_EQ(-1, Lookup(100));
105 ASSERT_EQ(201, Lookup(200));
106 ASSERT_EQ(1, deleted_keys_.size());
107 }
108
TEST_F(CacheTest,EntriesArePinned)109 TEST_F(CacheTest, EntriesArePinned) {
110 Insert(100, 101);
111 Cache::Handle* h1 = cache_->Lookup(EncodeKey(100));
112 ASSERT_EQ(101, DecodeValue(cache_->Value(h1)));
113
114 Insert(100, 102);
115 Cache::Handle* h2 = cache_->Lookup(EncodeKey(100));
116 ASSERT_EQ(102, DecodeValue(cache_->Value(h2)));
117 ASSERT_EQ(0, deleted_keys_.size());
118
119 cache_->Release(h1);
120 ASSERT_EQ(1, deleted_keys_.size());
121 ASSERT_EQ(100, deleted_keys_[0]);
122 ASSERT_EQ(101, deleted_values_[0]);
123
124 Erase(100);
125 ASSERT_EQ(-1, Lookup(100));
126 ASSERT_EQ(1, deleted_keys_.size());
127
128 cache_->Release(h2);
129 ASSERT_EQ(2, deleted_keys_.size());
130 ASSERT_EQ(100, deleted_keys_[1]);
131 ASSERT_EQ(102, deleted_values_[1]);
132 }
133
TEST_F(CacheTest,EvictionPolicy)134 TEST_F(CacheTest, EvictionPolicy) {
135 Insert(100, 101);
136 Insert(200, 201);
137 Insert(300, 301);
138 Cache::Handle* h = cache_->Lookup(EncodeKey(300));
139
140 // Frequently used entry must be kept around,
141 // as must things that are still in use.
142 for (int i = 0; i < kCacheSize + 100; i++) {
143 Insert(1000 + i, 2000 + i);
144 ASSERT_EQ(2000 + i, Lookup(1000 + i));
145 ASSERT_EQ(101, Lookup(100));
146 }
147 ASSERT_EQ(101, Lookup(100));
148 ASSERT_EQ(-1, Lookup(200));
149 ASSERT_EQ(301, Lookup(300));
150 cache_->Release(h);
151 }
152
TEST_F(CacheTest,UseExceedsCacheSize)153 TEST_F(CacheTest, UseExceedsCacheSize) {
154 // Overfill the cache, keeping handles on all inserted entries.
155 std::vector<Cache::Handle*> h;
156 for (int i = 0; i < kCacheSize + 100; i++) {
157 h.push_back(InsertAndReturnHandle(1000 + i, 2000 + i));
158 }
159
160 // Check that all the entries can be found in the cache.
161 for (int i = 0; i < h.size(); i++) {
162 ASSERT_EQ(2000 + i, Lookup(1000 + i));
163 }
164
165 for (int i = 0; i < h.size(); i++) {
166 cache_->Release(h[i]);
167 }
168 }
169
TEST_F(CacheTest,HeavyEntries)170 TEST_F(CacheTest, HeavyEntries) {
171 // Add a bunch of light and heavy entries and then count the combined
172 // size of items still in the cache, which must be approximately the
173 // same as the total capacity.
174 const int kLight = 1;
175 const int kHeavy = 10;
176 int added = 0;
177 int index = 0;
178 while (added < 2 * kCacheSize) {
179 const int weight = (index & 1) ? kLight : kHeavy;
180 Insert(index, 1000 + index, weight);
181 added += weight;
182 index++;
183 }
184
185 int cached_weight = 0;
186 for (int i = 0; i < index; i++) {
187 const int weight = (i & 1 ? kLight : kHeavy);
188 int r = Lookup(i);
189 if (r >= 0) {
190 cached_weight += weight;
191 ASSERT_EQ(1000 + i, r);
192 }
193 }
194 ASSERT_LE(cached_weight, kCacheSize + kCacheSize / 10);
195 }
196
TEST_F(CacheTest,NewId)197 TEST_F(CacheTest, NewId) {
198 uint64_t a = cache_->NewId();
199 uint64_t b = cache_->NewId();
200 ASSERT_NE(a, b);
201 }
202
TEST_F(CacheTest,Prune)203 TEST_F(CacheTest, Prune) {
204 Insert(1, 100);
205 Insert(2, 200);
206
207 Cache::Handle* handle = cache_->Lookup(EncodeKey(1));
208 ASSERT_TRUE(handle);
209 cache_->Prune();
210 cache_->Release(handle);
211
212 ASSERT_EQ(100, Lookup(1));
213 ASSERT_EQ(-1, Lookup(2));
214 }
215
TEST_F(CacheTest,ZeroSizeCache)216 TEST_F(CacheTest, ZeroSizeCache) {
217 delete cache_;
218 cache_ = NewLRUCache(0);
219
220 Insert(1, 100);
221 ASSERT_EQ(-1, Lookup(1));
222 }
223
224 } // namespace leveldb
225
226